The present invention relates to a device for regulating an ionic current or ion stream, particularly highly charged metal ions. This highly charged ion stream is more particularly used for measuring physical constants and particularly for equipping particle accelerators, used both in the scientific and medical fields.
One of the processes used for obtaining a highly charged or multicharged ion stream or ionic current consists of evaporating a solid material, e.g. a metal sample placed in an ultra-high frequency cavity and then ionizing the vapours produced.
The vaporization and then the ionization of the material are obtained by the interaction of a hot plasma of electrons, confined in said enclosure, with said material. This electron plasma is formed by ionizing a gas, injected into the cavity, as a result of the combined action of a high frequency electromagnetic field established in said cavity and a magnetic field prevailing within the same cavity. The magnetic field has an amplitude B satisfying the electron cyclotron resonance condition B=f.multidot.2.pi.(m/e), in which m is the mass of the electron, e its charge and f the electromagnetic field frequency. This resonance makes it possible to highly accelerate the electrons produced, firstly from the gas and then from the vaporization of the material.
This vaporization process was described in French patent application No. 2,512,623, filed on Sept. 10th, 1981 by the present Applicant and entitled "Process for the fusion and/or pulsed evaporation of a solid material". The metal ions produced can then be extracted from the cavity to form an ion beam.
In such a multicharged ion stream production process, one of the major problems is that of regulating the ion stream, i.e. in obtaining a constant intensity ion stream. This is very important, particularly when these ion streams are used in particle accelerators.